A275590 When written in English, the terms of the sequence with an odd number of letters form blocks whose sizes are given by the sequence itself.

1, 4, 2, 3, 6, 7, 5, 8, 10, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 26, 27, 28, 24, 25, 29, 30, 31, 32, 33, 36, 37, 38, 40, 34, 35, 39, 41, 42, 43, 44, 45, 49, 50, 54, 46, 47, 48, 51, 52, 53, 55, 59, 60, 64, 65, 69, 70, 74, 56, 57, 58, 61, 62, 63, 66, 67, 68, 71, 72, 73, 75, 79, 81, 82, 83, 86, 87, 88, 91, 92, 76, 77, 78, 80, 84, 85, 89, 90, 93

Offset

1,2

Comments

The sequence is started with a(1) = "ONE" and always extended with the smallest integer not yet used whose name in English does not lead to a contradiction.

The sequence is a permutation of the natural numbers.

The convention adopted here is to write the English number-names like "101" as ONE HUNDRED ONE and not ONE HUNDRED AND ONE (which would have produced a different sequence).

Links

Table of n, a(n) for n=1..93.

Index entries for sequences that are permutations of the natural numbers

Example

The blocks of "odd-words" are written in UPPER CASE letters and enclosed in parentheses; the successive block-sizes are 1, 4, 2, 3, 6, 7, ... which reproduces the sequence itself:
  (ONE), four, (TWO, THREE, SIX, SEVEN), five, (EIGHT, TEN), nine, eleven, twelve, thirteen, fourteen, (FIFTEEN, SIXTEEN, SEVENTEEN), eighteen, nineteen, twenty, (TWENTY-ONE, TWENTY-TWO, TWENTY-THREE, TWENTY-SIX, TWENTY-SEVEN, TWENTY-EIGHT), twenty-four, twenty-five, twenty-nine, thirty, (THIRTY-ONE, THIRTY-TWO, THIRTY-THREE, THIRTY-SIX, THIRTY-SEVEN, THIRTY-EIGHT, FORTY), thirty-four, ...

Crossrefs

Sequence in context: A361747 A282865 A241051 * A338844 A333406 A083181

Adjacent sequences: A275587 A275588 A275589 * A275591 A275592 A275593

Keyword

nonn,word,base

Author

Eric Angelini, Aug 02 2016

Status

approved